Nick Clegg thought he was onto a winner with "alarm clock Britain" - his description for the "squeezed-middle".

He was trying to appeal to us hard workers getting up early in the morning. But despite repeating it on several occasions, it never really took off.

While ancient Rome certainly didn't get it all right, its politicians were at least trying to persuade voters of a particular argument.

He'd forgotten that most of us don't wake up to alarm clocks anymore - more likely some pre-selected music.

Sometimes, though, the political class hit on something catchy. Party leaders are tripping over themselves to help the nation's "hard-working families".

But, in my experience, it's a slogan everyone seems to hate.

That's partly because an awful lot of people don't think of themselves as a family, and "hard-working" has a dreadful smack of the workhouse about it.

While ancient Rome certainly didn't get it all right, its politicians were at least trying to persuade voters of a particular argument.

If persuasion isn't at stake, we may as well just vote on the basis of our own existing prejudices. Politicians need to think about how they can change people's minds, not just reflect what they already think.

In the 1960s, Labour MP Roy Jenkins was one of the most revolutionary home secretaries the UK has ever had. It might have been the swinging sixties, but the views of most voters were far from swinging.

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Mr Jenkins needed to persuade people to sign up to the end of capital punishment and to decriminalise homosexuality.

He did not need voters to be overwhelmingly positive about what he wanted to do, but he did use argument to persuade them to at least accept it.

His speech on immigration - a hugely political issue in the 60s just as it is today - is a prime example:

"Let there be no suggestion... that immigration, in reasonable numbers, is a cross that we have to bear, and no pretence that if only those who have come could find jobs back at home our problems would be at an end."

Margaret Thatcher was certainly one who used borrowed words and slogans. But, for better or worse, she was a persuasive politician who invested a lot in the ideas and the argument.